[Air-L] Looking for the data about google's market share in the search engine market

Hi everyone. This is my first post to Air-L. I've been trying to find the data about the market share of Google in the search engine market. Can anyone let me know where can I find the country-specific Google's market share in the search engine market (from 2007 to 2012)? Thank you Best regards, Sung Wook Ji Visiting Assistant Professor Dept. of Telecommunication, Information Studies and Media Michigan State University